Utilization of SPECT/CT for the evaluation of suspected acute cholecystitis in problematic cases

Objectives To retrospectively evaluate our institutional experience with SPECT/CT hepatobiliary imaging as a problem solving tool in the work up of suspected acute cholecystitis.

Methods This retrospective study was approved by the institutional review board. A total of 53 consecutive patients who had SPECT/CT in addition to planar imaging were included. This cohort represents cases which were considered problematic by the initial interpreting physician based on planar images. The planar and SPECT/CT images were retrospectively reviewed independently by two experienced nuclear medicine specialists who evaluated the planar images for visualization of the gallbladder and rated their level of confidence. At a separate session, they repeated the assessment for the SPECT/CT images.

Results There was poor inter-observer agreement in reading the planar images in (54.7%; Kappa= 0.10), whereas, the inter-observer agreement in reading the SPECT/CT images was high (94.3%; Kappa= 0.87). The intra-observer agreement for the planar and SPECT/CT interpretations for the two readers were 58.5% (Kappa= 0.005) and 56.6% (Kappa= 0.14). The SPECT/CT would have led to change in the management for interpreter (1) in a total of 22 cases (41%) with change from normal to abnormal scan (28%) and from abnormal to normal scan (13%). Similarly, SPECT/CT would have led to change in the management for interpreter (2) in a total of 23 cases (43%) with change from normal to abnormal scan (13%) and from abnormal to normal scan (30%).

Conclusions Although hepatobilary scanning with planar imaging is usually sensitive and specific there are occasionally problematic cases. We found that SPECT/CT improves the inter-observer agreement and changes management in select patients with superimposed bowel activity and/or unusual gallbladder anatomy which can confound the planar interpretation